1. Field of the Invention
The present invention relates to a device for detecting radiation within a pipe. More specifically, it relates to a device that is pulled through embedded piping to perform radiation surveys therein.
2. The Prior Art
Nuclear facilities within the United States are licensed for operation by the Nuclear Regulatory Commission (NRC). The NRC specifies radiation contamination limits, for example, radioactive contamination limits that must be satisfied prior to termination of an NRC license. Modern nuclear power stations contain thousands of feet of exposed and embedded piping that must be surveyed in order to determine radioactive contamination levels. The cost of removing this piping is many millions of dollars, and therefore it would be advantageous to survey the internal pipe surfaces while the pipes remain embedded, for the purpose of allowing unconditional release of those pipes.
The radiation survey is most effectively carried out by a pipe crawler or a device with radiation sensors that is located within the pipe. These devices are equipped with a variety of detectors, to count alpha, beta particles and/or gamma rays. A different size pipe crawler is required to survey each size of pipe and even each schedule of pipe size.
Numerous patents have been issued pertaining to equipment for testing the integrity of pipes and pipe joints. For example, U.S. Pat. No. 4,131,081 to Muller et al, U.S. Pat. No. 4,548,785 to Richardson et al, and European Patent Application 039,922 disclose devices for ultrasonically inspecting pipes. U.S. Pat. No. 4,581,938 to Wentzell, U.S. Pat. No. 5,138,644 to McArdle et al, French Patent 2,652,650 and European Patent Application 078,072 disclose various other types of scanning and measuring equipment for pipes. However, none of these patents addresses the specific problems associated with detecting radiation within pipes.
Therefore, it would be advantageous to have a device that can pass within piping and detect radiation contamination on the internal surfaces of those pipes. It would be further advantageous to have a device that can perform detailed radiological surveys at precise locations of internal pipe surfaces. It would further be advantageous to be able to survey different size pipes and different schedules of pipes.